As development of a wireless transmission technology, a transmission speed of wireless data has increased. Nowadays, a high-speed downlink packet access (HSDPA) service supports 2 Mbps and 14.4 Mbps at an uplink and a downlink, respectively, and wireless broadband (WiBro) supports 6 Mbps and 19.97 Mbps at an uplink and a downlink, respectively. Further, WiBro-evolution (WiBro-EVO) expected to appear in the near future is expected to support 50 Mbps at an uplink and a downlink, respectively.
In this way, as a data transmission amount to be processed by wireless terminals increases, it is necessary to develop a wire transmission network for transferring the data. As a characteristic of a wireless technology for supporting a large amount of wireless data, such as worldwide interoperability for microwave access (WiMAX) or WiBro, downlink data are transferred to a plurality of access points (AP) using a broadcasting method and are wirelessly transmitted to a subscriber terminal, however uplink data wirelessly transmitted from a plurality of subscriber terminals are primarily collected at a plurality of APs, and each of the APs transmits the corresponding data to the center using a wire.
Conventionally, the center and the AP were connected in a point-to-point form. However, when the APs are locally condensed, there is a problem that a point-to-point connection between the center and the APs uses many optical fibers.